The present invention relates generally to compositions for absorbing liquid wastes in animal litters, and more particularly to a litter composition that agglomerates into a mass upon contact with a liquid.
Animal litter compositions, such as cat litter, are well known for collecting urine and feces of house-broken animals. Conventional litter compositions include absorbent materials such as clays, paper, wood chips, organic fiber, etc. When odors from the animal waste in the litter become objectionable, the fecal matter may be physically removed from the litter. However, in order to remove the odors caused by the urine, it has been necessary to discard the entire litter composition, including the unsoiled litter, and replace the litter box with fresh litter.
In order to reduce the inconvenience and expense of replacing the entire litter material, recent litter compositions have included substances which agglomerate or gel when wetted to form a mass, thereby permitting the soiled litter to be conveniently separated from the unsoiled litter. Such substances include swelling clays such as bentonite and other swelling montmorillonites which are disclosed, for example, in U.S. Pat. No. 5,000,115, issued to Hughes. The litter composition of Hughes preferably includes bentonite clay in an amount of at least 65% by weight of the total composition. Essentially, the bentonite clay agglomerates when wetted to permit physical removal of the wetted litter box absorbent material from the "unwetted" material. One problem with swelling clays is that they must be of a type that can be processed into animal litters. Thus, selective mining may be required in order to obtain a good quality of swelling clay, thereby raising the cost of the litter material. Furthermore, the ability of a swelling clay to solidify urine can be negatively affected by the electrolytes present in urine.
In addition to swelling clays, additives may be provided to conventional absorbent litter materials to agglomerate the animal urine into a removable mass. In U.S. Pat. No. 4,685,420, issued to Stuart, there is disclosed a litter box absorbent composition in which 0.01% to 5% by weight of the composition is a water-absorbing polyacrylate. The remainder of the litter composition is an inert solid substrate made of conventional litter box absorbent materials. The polyacrylates act to gel the soiled litter box absorbent material into a gelled product. The gelled absorbent material can then be physically removed from the litter box to reduce the generation of offensive odors and to avoid discarding the unsoiled portion of the absorbent material. A problem with these additives is that they are relatively expensive, thereby raising the cost of the litter material to unacceptable levels.
It is desired to provide an absorbent material which is cost effective yet also overcomes the problems associated with the above swelling clays and clumping additives.